Process of and apparatus for electrically making holes in metal blocks or plates.



I. L. MURRAY, Ba. PROCESS OF AND APFARATUS'FOR ELECTRICALLY BIAKIIIG HOLES m METAL BLOCKS 0a PLATES.

APPLICATION FILED APR. 24, ISU- 15233Q690. Patentefi July 1?, 1917.

INVENTOR 4624/ GM ATTOR EI circular opening C. The straight UNITED STATES PATENT OFFICE.

THOMAS E. MURRAY, JR, OF BROOKLYN, NEW YORK.

OR PLATES.

PROCESS OF'AND APPARATUS FOR ELECTRICALLY MAKING HOLES IN METAL BLOCKS Application filed April 24, 1917.

To all whom it may concern:

Be it known that I, THOMAS E. MURRAY, Jr., a citizen of the United States, residing at-Brooklyn, in the county of Kings and State of New York, have invented a certain new and useful Improvement in Processes of and Apparatus for Electrically Making Holes in Metal Blocks or Plates, of which the following is a specification.

The invention is a process and an apparatus for electrically making holes in metal blocks or plates.

The principle of my invention depends upon the fact that when the plate or block to be pierced is placed upon two separated electrodes having registering recesses in their opposing faces, and a current of suitable strength is, caused to pass through said electrodes and plate, the metal of the plate which covers the opening formed by said registering recesses is softened, so that a punch adapted to enter said opening may be caused to remove said metal by forcing 'the same as a core out of said opening, thus making an opening in said plate or block.

In the accompanyingdraw'ings- Figure 1 is a vertical section through the electrodes and plate to be pierced, showing the movable punch in elevation and raised. Fig. 2 is a similar view, showing the punch in the opening between the electrodes. Fig. 3 is a perspective view of the metal plate with the hole made therein.

Similar letters of reference indicate like parts.

A and B are the electrodes, in the opposing edges or faces of which are semi-circular recesses which unitedly form a substantially portions of said edges on each side of said recesses are separated by a narrow air gap D. E is a punch supported in any suitable way for vertical movement above the opening C.

Said punch is adapted to enter and move in the opening G with small clearance. The plate F, in which the hole is to be made, is

' placed upon the electrodes A, B, and covers the opening C. When current of suitable Specification of Letters Patent.

Patented July 17, 1917'. Serial No.- 164,132.

strength is established, it passes from one electrode to the other through the metal of that portion of plate E which covers the opening C and is directly below the end of punch E, and causes a softening of said metal, so that the punch in descending forces out a cylindrical core of said softened metal through said opening 0, thus producing a hole G in the plate F. By reason of its sliding contact with the metal of the plate surrounding the hole, said punch also trues and smooths the inner surface of said metal, so that the cross sectional area of the hole accords with that of the punch. In this way I am enabled to make accurately formed holes in the plate, which need no further reaming or other treatment, unless it be desired for special reasons to enlarge them.

I claim:

1. Making an opening in a stationary metal block or plate by electrically heating a definitely circumscribed portion of said plate to soften the same, and then immediately subjecting said softened portion to mechanical pressure to remove a core having across sectional area corresponding to said circumscribed portion from said softened portion.

2. Making an opening in a stationary in their opposing faces registering transverse recesses, and a longitudinally movable punch adapted to enter the openingformed by said recesses.

In testimony whereof I have aiiixed my signature in presence of two Witnesses.

THOMAS E. MURRAY, JR. Witnesses:

GERTRUDE T. Pon'mn, MAY T. MoGARRY. 

